linux-kernel - Re: [v5] PCI: imx: make msi work without CONFIG

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Message-ID: <20181220144956.GA7041@e107981-ln.cambridge.arm.com>
Date:   Thu, 20 Dec 2018 14:49:56 +0000
From:   Lorenzo Pieralisi <lorenzo.pieralisi@....com>
To:     Richard Zhu <hongxing.zhu@....com>
Cc:     "bhelgaas@...gle.com" <bhelgaas@...gle.com>,
        "l.stach@...gutronix.de" <l.stach@...gutronix.de>,
        "andrew.smirnov@...il.com" <andrew.smirnov@...il.com>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [v5] PCI: imx: make msi work without CONFIG_PCIEPORTBUS=y

On Wed, Dec 19, 2018 at 04:45:04AM +0000, Richard Zhu wrote:
> Assertion of the MSI Enable bit of RC's MSI CAP is mandatory required to
> trigger MSI on i.MX6 PCIe.
> This bit would be asserted when CONFIG_PCIEPORTBUS=y.
> Thus, the MSI works fine on i.MX6 PCIe before the commit "f3fdfc4".
> 
> Assert it unconditionally when MSI is enabled.
> Otherwise, the MSI wouldn't be triggered although the EP is present and
> the MSIs are assigned.
> 
> Signed-off-by: Richard Zhu <hongxing.zhu@....com>
> Reviewed-by: Lucas Stach <l.stach@...gutronix.de>
> ---
> Changes v1 -> v2:
> * Assert the MSI_EN unconditionally when MSI is supported.
> Changes v2 -> v3:
> * Remove the IS_ENABLED(CONFIG_PCI_MSI) since the driver depends on
> PCI_MSI_IRQ_DOMAIN
> * Extended with a check for pci_msi_enabled() to see if the user
> explicitly want legacy IRQs
> Changes v3 -> v4:
> * Refer to Bjorn's comments, refine the subject and commit log and change
> the PCI_MSI_CAP to PCIE_RC_IMX6_MSI_CAP.
> Changes v4 -> v5:
> * Correct one spell mistake from PCIE_RC_MSI_IMX6_CAP to
> PCIE_RC_IMX6_MSI_CAP.
> ---
>  drivers/pci/controller/dwc/pci-imx6.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
> index e563ca9..73542dd 100644
> --- a/drivers/pci/controller/dwc/pci-imx6.c
> +++ b/drivers/pci/controller/dwc/pci-imx6.c
> @@ -82,6 +82,7 @@ struct imx6_pcie {
>  #define PHY_PLL_LOCK_WAIT_USLEEP_MAX	200
>  
>  /* PCIe Root Complex registers (memory-mapped) */
> +#define PCIE_RC_IMX6_MSI_CAP			0x50
>  #define PCIE_RC_LCR				0x7c
>  #define PCIE_RC_LCR_MAX_LINK_SPEEDS_GEN1	0x1
>  #define PCIE_RC_LCR_MAX_LINK_SPEEDS_GEN2	0x2
> @@ -999,6 +1000,7 @@ static int imx6_pcie_probe(struct platform_device *pdev)
>  	struct resource *dbi_base;
>  	struct device_node *node = dev->of_node;
>  	int ret;
> +	u16 val;
>  
>  	imx6_pcie = devm_kzalloc(dev, sizeof(*imx6_pcie), GFP_KERNEL);
>  	if (!imx6_pcie)
> @@ -1149,6 +1151,14 @@ static int imx6_pcie_probe(struct platform_device *pdev)
>  	if (ret < 0)
>  		return ret;
>  
> +	if (pci_msi_enabled()) {
> +		val = dw_pcie_readw_dbi(pci, PCIE_RC_IMX6_MSI_CAP +
> +				PCI_MSI_FLAGS);
> +		val |= PCI_MSI_FLAGS_ENABLE;
> +		dw_pcie_writew_dbi(pci, PCIE_RC_IMX6_MSI_CAP +
> +				PCI_MSI_FLAGS, val);
> +	}
> +
>  	return 0;
>  }

Hi Richard,

the patch is OK with me (even though I have to take for granted how the
IMX MSI logic works), the commit log isn't. So please update it with
Bjorn's version:

https://lore.kernel.org/linux-pci/20181219141241.GB12763@google.com/

*inclusive* of the Fixes: tag.

With the commit log updated as per the link above:

Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@....com>